Left, Right and Centre

Much talk over the weekend of whether or not the Tories would take a 'lurch to the Right' after the unfortunate events at Eastleigh. Why is any movement to 'the Right' (whatever that is) described as a 'lurch' - desperate, uncontrolled, uncoordinated? Whatever happened to the good old (pleasingly alliterative) 'lurch to the Left'? It seems a long time since anyone in British politics proposed any movement in that direction... Does this tell us something - perhaps that the Centre is now situated somewhat to the Right of where it once was? Will the Tories therefore be lurching (or not) toward the Centre? What kind of a lurch is that?